The present invention relates to an apparatus and a method for manufacturing liquid crystal display (LCD), and in particularly, to an apparatus and a method for applying an alignment liquid and spacers in manufacturing LCD.
With the rapid progress of information technology, the thin film transistor liquid crystal display (TFT LCD) is replacing the cathode ray tube (CRT) display to be the mainstream in the market. Meantime, the glass substrate for the TFT LCD is also becoming larger in dimension, which brings more challenge to the processing of the substrate.
In a conventional manufacturing process for the LCD, an alignment layer forming liquid (hereafter referred to as “alignment liquid”) is generally applied with a transfer printing method. As shown in FIG. 1, the alignment liquid is first introduced onto a rotating anilox roller 3 from a nozzle 1, and the alignment liquid is further uniformly coated onto a transfer printing roller 4 with the assistance of a doctor roll 2. The roller 4 is rotated and subsequently brought into contact with a glass substrate 5 disposed on a stage 6 under a certain pressure, so that the alignment liquid coated on the roller 4 is transferred onto the glass substrate 5. After transferring of the alignment liquid, the formed alignment layer is mechanically rubbed with a rubbing device so as to have a uniform arrangement and predetermined orientation.
After the alignment layer is prepared, spacers are distributed, for example, by a dry distributing method on the glass substrate 5 for maintaining a uniform thickness of the crystal layer of the LCD, and then an assembling process of the substrates is performed. As shown in FIG. 2, after filtered in a filter device 7, spacers are delivered to a spray head 8, during which course the spacers are charged with same polar charge to avoid agglomeration of the spacers in spraying. The spacers are sprayed onto the glass substrate 5 loaded on a support 10 through the spray head 8 with a certain gas pressure. The gas and spacers outside the glass substrate 5 are discharged outside through a gas pump 11.
However, there exist several intrinsic disadvantages in the related art, such as difficulty to maintain a uniform thickness of the alignment layer, scratches, particle contamination, electrostatic discharge damages, etc., which tend to occur during rubbing on the alignment layer. Further, the dry distributing method brings problems of uneven distribution and agglomeration of the spherical spacers. In addition, as the size of the glass substrate becomes larger, the problems are more apparent. A method for spraying spacers with the alignment liquid is disclosed, for example, in Chinese patent application No. 93106295.0, which solves the problem of spacers agglomeration and simplifies the manufacturing process. However, the method, which makes use of a high speed rotating stage, is difficult to obtain a uniform thickness of the alignment layer and also is prone to contaminate the apparatus. Also, in the method, the subsequent rubbing process tends to move the spacers, and the alignment layer may not be rubbed in a uniform manner. These problems if not controlled properly will greatly degrade the image quality of the LCD, leading to light leakage and brightness uniformity. Thus, there is a need to improve the manufacturing process.